I think he will stay in broadcasting.
I don't think any NFL team or Division 1 school is likely to hire a soon-to-be 73-year-old coach. NFL teams and colleges invest heavily in infrastructure around a head coach, with the expectation that it will remain in place for several years. At 73, concerns about health and the inevitable effects of aging arise.
Why do I bring this up? I believe that if Wade Phillips were younger, he would have been an NFL head coach in recent years—especially considering the success he had with the Rams' SB defense. After that, you know what he did? He became the head coach of a UFL team, where he performed quite well, and that was it.